As more and more vehicles are equipped with supplemental inflatable restraint (SIR) systems, other vehicle components have been modified to accommodate the use of such systems. For example, most SIR systems are disposed within and behind an instrument panel which extends across the width of a vehicle compartment. Generally, a vehicle instrument panel comprises a plurality of layers including a panel cover, a foam layer, and a substrate. The cover is typically disposed adjacent the foam layer which is disposed, correspondingly, adjacent to the substrate, thus forming the panel.
Traditionally, an instrument panel employed in a vehicle equipped with a SIR system utilizes a discrete door which covers an opening formed in the instrument panel for the airbag cushion to deploy through upon actuation of the SIR system. This separate door is designed to open in response to the force of the expanding airbag cushion. As the pressure in the airbag cushion increases, a force is generated on the door. The door then selectively separates from the remaining portion of the instrument panel to permit the airbag cushion to deploy.
Typically, the manufacture of a conventional instrument panel involves two separate processes and a final assembly step. First the instrument panel is formed in view of the shape and size of the door with an opening adjacent to the SIR system. Meanwhile, in a separate process the door is formed using techniques known in the art. Finally, the airbag door is assembled onto the instrument panel for use in conjunction with the SIR system. The plurality of steps involved in the manufacture of the conventional instrument panel consume substantial time and resources and result in an aesthetically apparent airbag door.
Recent advances in the art teach a vehicle instrument panel that utilizes a hidden deployment region integrally formed within an inner surface of the instrument panel to provide a panel of less weight and without the obvious markings of an airbag door. The deployment region of such panels comprises a plurality of scores or cuts formed in the inner surface of the instrument panel. The scores represent weakened portions of the instrument panel designed so that the force of an inflating airbag cushion causes the instrument panel to separate along the scores to thereby provide an opening for the inflating airbag cushion to deploy therethrough and be directed into the passenger compartment of a vehicle.
The manufacture of vehicle instrument panels with integrally formed hidden airbag doors typically involves three distinct processes. First, the various layers of the panel are cast using methods common in the art. Then, a blade is brought into contact with the various cast layers of the panel to melt and/or cut into the interior surface of the layers forming the scores and cuts necessary to allow deployment of the concealed airbag. Finally, the layers are adhered together in such a way as to construct the panel.
To date, hidden airbags have been provided for vehicle OEMs in several different design and manufacturing configurations. However, none of them have combined a hidden passenger airbag (PAB) door having a chute wall molded as one piece into the instrument panel (I/P) substrate, thus reducing overall part costs, mass and dimensional variation. These goals have driven the need to develop a tear seam that would allow the airbag to deploy correctly while maintaining structural rigidity for occupant abuse. The airbag door must cover and prevent occupant access to the airbag and its inflator until a deployment event. During the deployment event, the door must open and clear itself from the path of the inflating airbag. This dual purpose requires the perimeter of the airbag door to be relieved in some manner to prevent access, yet allow proper deployment of the airbag.
The relief is typically created by removing the majority of the molded plastic I/P substrate defining the tear seam of the door. At predetermined locations, a small amount of material is left as molded to hold the door in place until deployment. These uncut sections are called “nubbins”. The nubbins are required to provide the structural rigidity needed to prevent a occupant from incidently opening the hidden airbag door. However, the nubbins break in an unpredictable direction and shape during a PAB deployment event and risk snagging and/or tearing the airbag.
Accordingly, it is desired to mold an integral PAB door and chute wall that effectively eliminates the negative effects of previous nubbin designs while still maintaining the ability to prevent the occupant abuse type of PAB door opening without having to add component parts to the design.